crypto: deduplicate X509 subject matching logic

[tniessen]

CheckHost(), CheckEmail(), and CheckIP() all do very similar things. Extract the common logic into a helper function CheckX509Subject() to avoid duplication.

[nodejs-github-bot]

Review requested:

• @nodejs/crypto

[codecov]

Codecov Report

❌ Patch coverage is 88.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.30%. Comparing base (4639dcb) to head (2815b81).
⚠️ Report is 15 commits behind head on main.

Files with missing lines	Patch %	Lines
src/crypto/crypto_x509.cc	88.00%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #63644    +/-   ##
========================================
  Coverage   90.29%   90.30%            
========================================
  Files         730      730            
  Lines      234695   234795   +100     
  Branches    43956    43951     -5     
========================================
+ Hits       211927   212037   +110     
+ Misses      14494    14484    -10     
  Partials     8274     8274            

Files with missing lines	Coverage Δ
src/crypto/crypto_x509.cc	73.63% <88.00%> (+1.18%)	⬆️

... and 61 files with indirect coverage changes

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